The invention relates to an concrete anchor bolt for high-tensile interconnection of two solid bodies in a concrete-to-concrete bond.
In a concrete-to-concrete bond the concrete anchor bolt, together with its fixing member, is installed using a temporarily fluid, settable fixing agent, such as a reaction resin mortar, in a blind tapped borehole in a first solid body, such as set concrete, and with a radially projecting connecting element embedded in the first body, and using a subsequently setting, second solid body, such as fresh concrete.
At the utilization site, prefabricated angled or conically ended closed reinforcement iron pieces as well as threaded plates together with threaded bars are conventionally used on site. The concrete anchor bolts are not optimally designed with respect to their resistance to extraction of the connecting element from the fresh concrete or the tensile or tractional force transmission in same as well as the tensile rigidity.
As disclosed in WO99/61716, a conical capping member screwed onto a threaded rod is embedded in fresh concrete, whereby the conical capping member readily ends flush with the surface of the fresh concrete and only bonds with the fresh concrete with respect to the poorly adhering conical surface. The conical capping element forms a double radial angle at an axial half-angle of 15xc2x0 along its axial length. The conical capping element is not optimized for force transmission but serves as a negative mold that can be easily removed with respect to the surface of the fresh concrete.
CH684648A5 discloses threaded sleeves comprised of plastic and having circumferentially distributed conical ribs having an axial half-angle of 45xc2x0 and double radial angle along their axial length embedded in fresh concrete. Only minimal tensile or tractional loads can be applied in the case of plastic threaded sleeves.
Further, DE2355799 discloses wavelike tubular elements embedded in fresh concrete and combined with other structural components by threading.
The object of the present invention is a technically simplified embodiment of a concrete anchor bolt having an optimized geometry with respect to tensile force transmission and tensile rigidity.
Essentially, a concrete anchor bolt comprises an axially extending, connecting or fixing member that can be fixed in a blind hole in a first solid body using a temporarily fluid, settable fixing agent and a radially projecting conically shaped section that is embedded at a later point in time in a setting second solid body and forms a part of the fixing member.
The conically shaped section is oriented rotationally symmetrically diagonally to the direction of loading of the conically shaped section and is made extremely rigid by the concrete filling and results, at the time of tensile or tractional loading of the anchor bolt, in loading favorable to concrete within the conical region and thus in force transmission adapted to the material properties of concrete.
Advantageously, according to pre-testing, the axial half-angle is in the range of 20xc2x0 to 40xc2x0, in the simulated ideal situation is 30xc2x0, which results in an optimal force transmission in the material concrete.
The radial angle, determined as the relation of the end diameter the axial length of the conical sleeve, advantageously is in the range of 2, 5 to 5, whereby the axial tensile or tractional loading derived with respect to the fixing section of the anchor bolt is completely transformable into compressive loading of the normally oriented conical region without locally exceeding permissible compressive strength limits.
The conically shaped section is advantageously formed hollow with essentially uniform wall thickness, and can be manufactured in a technically simple manner and thus economically by punching and shaping processes in large numbers and further advantageously produced from sheet iron or iron tube ends of several mm thickness.
The conically shaped section is advantageously produced as a separate structural member piece for material-bonding by welding or for axially form-locked connection by screw-on or by rotational engagement or locking using a special axial aperture designed as a connector and/or guide established at the smaller surface as a connector and/or guide arranged on a special residual anchor bolt, whereby a simple combination of system components addressing the requirement can be formed at the utilization site.
The special axial opening of the conical sleeve is advantageously designed for connection to an axially extending region of the anchor bolt and provides an axial projection of the residual anchor bolt over the overall coverage surface of the conical sleeve, so that when hammering the anchor bolt into the tapped blind borehole the impact is not made directly on the conical sleeve and avoids damaging it.
An advantageous alternative is created if the conically shaped section is prefabricated as a unit with the anchor bolt, whereby the predetermined fracture points limiting force transmission at material-bonding or form-locking connection points are provided, which avoids the combination of a separate conically shaped section with the residual anchor bolt at the utilization site.
The conical sleeve is advantageously made as a radially expandable terminal section of a tubular section forming the anchor bolt, whereby a smooth transmission of force into the wall of the tube is possible without scoring or notching that limits force transmission.